According to the vendor, Inteno DG301 is a high-end Multi-WAN residential gateway with advanced router and bridge functions.

2. Summary

Inteno DG301 Powered by LuCI Trunk (inteno-1.0.34) and OpenWrt Backfire 10.03.1-RC6 is vulnerable to command injection, which can be exploited directly from the login form on the web interface.

The vulnerability could be exploited by unauthenticated attackers.
Successful exploitation would allow attackers to execute arbitrary commands with root privileges.

3. Affected Products

DG301 Powered by LuCI Trunk (inteno-1.0.34) and OpenWrt Backfire 10.03.1-RC6.
Other products or previous versions may also be vulnerable.

4. Vulnerability and Proof of Concept (PoC)

The login form presented on the web administration interface (username parameter) is vulnerable to command injection, due to the application does not validate the user input in a proper manner.

The following PoC includes a POST request that should be sent to the device via web. The request includes a command that will copy the contents of "/etc/passwd" to a file "test.txt" on the root web folder were the web administration interface is published.

After the request is sent, proceed to visit http://<routerIP>/test.txt.
This should display the contents of "/etc/passwd", including the root password in encrypted (DES) form. From here, the root credentials could be cracked in a reasonable amount of time. This attack could also be used for enabling services (e.g. SSH), or running any other arbitrary commands.

A general implementation of this PoC can be found here:
http://www.encripto.no/tools/inteno-DG301-PoC.tar.gz

5. Remediation

The vendor has released a new firmware version - 1.6.8RC3.
Users are encouraged to update their devices in order to patch the
vulnerability.

6. Credit

The vulnerability was originally discovered in an Inteno DG301 device (manufactured Nov. 2013), by Juan J. Güelfo at Encripto AS.

For more information about Encripto's research policy, please visit http://www.encripto.no/forskning/

7. Timeline

24th of January 2014 - Vulnerabilities discovered by the researcher.
26th of January 2014 - Vulnerability details disclosed to the vendor.
31st of January 2014 - New firmware version launched by the vendor, which addresses the vulnerability.
3rd of February 2014 - Public disclosure.

The material presented in this document is for educational purposes only. Encripto AS cannot be responsible for any loss or damage carried out by any technique presented in this material. The reader is the only one responsible for applying this knowledge, which is at his / her own risk.

Any of the trademarks, service marks, collective marks, design rights, personality rights or similar rights that are mentioned, used or cited in this document is property of their respective owners.